Fuel pump diaphragm leakage indicator



. Dec. 8,1970

R. E. KALERT, JR 3,546,690

FUEL PUMP DIAPHRAGM LEAKAGE INDICATOR Filed Oct. 31, 1967 FlGLl.

O 33 v F I J. Z7\ 25 34 INVENTOR RALPH E. KALERT JR. 32. 37

ATTORNEY United States Patent Oil" US. Cl. 340-242 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a mechanically actuated diaphragm fuel pump which includes an electrically operated alarm system adapted to provide warning or indication that the diaphragm or other part of the pump is damaged to the extent that leaking fuel has passed the diaphragm. The fuel leak sensor comprises in effect a switch connected to a source of electricity, and an alarm mechanism. The alarm is actuated in response to the deformation or deterioration of a retaining member which, when suificiently deformed or deteriorated due to contact with fuel or fuel vapors will permit the switch to close and actuate the alarm circuit.

BACKGROUND OF THE INVENTION The field of this invention lies primarily in fuel systems and more particularly with respect to the pumping means normally employed in fuel systems. The pump presently disclosed includes a reciprocating, flexible diaphragm used as the movable Wall of the pumping chamber for urging fuel from a source, through the pump discharge. The diaphragm member is normally formed of a nonmetallic material or composition to permit the needed flexibility during motion. Such materials include reinforced fabric, rubber and the like. The diaphragm member might be considered as the Weakest link in the pump structure with respect to wear or deterioration. It is understandable that over a period of time continuous flexing of the diaphragm will cause cracking and eventual rupturing-of the material which will permit passing of fuel from the pumping diaphragm into the adjacent chamber.

The problem of fuel pump leakage or breakdown is particularly vexing in the instance of automobiles, boats,

and other engine powered vehicles. Since the fuel pump diaphragm is relatively inaccessible, once the diaphragm has ruptured to the extent that it no longer functions to urge fuel from the source into the carburetor, the supply of fuel to the engine is stopped. In many instances however the diaphragm does not rupture to the extent of rendering the pump immediately inoperative. Rather as a rule, the diaphragm initially develops a fissure which is gradually enlarged to the point where it permits a slight passage of fuel from the pumping chamber, which passage gradually enlarges due to further aggravation during dia phragm motion.

A further hazard common to fuel systems and related to the malfunction of the pump is the danger of vapor accumulations within a closed area. This is most prevalent on boats which are often constructed in a manner which minimizes the ventilation of the engine and consequently promote the accumulation of volatile vapors within an enclosed area.

It is thus understandable, that if some pre-warning could be given of the imminent breakdown of the fuel pump, much trouble might be averted by timely repair, or replacement. Notably, if the initially damaged diaphragm could be replaced, or preferably the entire pump be replaced when the latter first shows signs of wear, the above noted problems would be obviated.

3,546,690 Patented Dec. 8, 1970 ICC SUMMARY The inventive concept instantly disclosed embodies an alarm system incorporated into a fuel pump for sensing fluid in other than the pumping chamber. This alarm system comprises generally a sensor mechanism including a switch, removable from the pump and connectable into an electrically powered alarm circuit having a suitable indicator device such as a bell or a warning light. The sensor member embodies at least one contact forming the switch and connected in series with the alarm circuit. Said one contact member includes a spring means biasing the latter toward a second contact member such that upon electrical engagement of the two, the alarm circuit will be closed to actuate the alarm indicator. For normal operation, the second contact is maintained in spaced relation to the first contact by an expandable or deteriorative member which is characterized by being subject to physical deterioration or expansion when exposed to an atmosphere of either pumped fluid or vapors of said fluid. For the purpose of safety the switch contact is sealably insulated from the pump atmosphere which could become explosive due to fuel leakage.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation view in partial cross-section of a fuel pump of the type presently contemplated embodying a sensor switch connected to an electrically powered alarm circuit.

FIG. 2 is an enlarged view in cross-section of the sensor switch removably carried in a Wall of the fuel pump.

FIG. 3 is similar to FIG. 2 with the exception that the contact retainer is shown removed and the movable contact shown in its retracted position within the sensor body.

FIG. 4 is a schematic diagram of the alarm circuit as connected with an engine ignition circuit.

DESCRIPTION OF THE INVENTION The fuel pump shown in FIG. 1 of the drawing is typical of a mechanically actuated diaphragm type pump which might incorporate the present fuel alarm system. The pump is similar in operation and structure to the pump shown in US. Pat. 3,333,547, D. R. Compton et al. The function and operation of such a pump is fully described in said patent. However, the basic pumping mechanism in this type of device resides in the use of a diaphragm maintained between the pump two halves, and actuated by a spring biased mechanism. The latter is in turn operably connected to a rotating part of the engine so that the pump speed might be varied with engine speed.

As shown in the drawings, the diaphragm must be operated in such manner as to provide an expanding wall chamber. Thus, the diaphragm is subjected to a continuous flexing motion adjacent the periphery. This continuous motion tends to prompt the formation of cracks and fissures along or near the periphery which generally form into openings which lead to fuel leakage.

Referring to FIG. 1, the pump consists basically of a housing 10 which defines a cavity 11 and from which depends a casing 12. The edge of the latter is connected to the open side of housing 10 thereby defining an enclosure. Housing 10 embodies a peripheral lip 13 forming an opening to cavity 11. Casing 12 includes a rim 14- complementing lip 13 and abutting the latter to form a fluid tight circumferential seal.

The casing is provided with formed wells not presently shown but which house inlet and outlet valves so disposed to regulate liquid flow through the pumping chamber.

A diaphragm 16 is compressibly held at its periphery intermediate the tightly clamped edges of rim 14 and lip 13. Diaphragm 16 is further maintained sufliciently tight at the edge to form a fluid tight seal thereby defining the spring chamber 17 and pumping chamber 18 on opposite sides thereof. Diaphragm 16 may be partially rigidized by oppositely disposed plates 19 and 21 which extend across the respective surfaces. The lower plate, as well as the upper, are so formed at their periphery to impart the diaphragm a particular curved configuration as the latter is urged into its displaced position during the pumping movement.

A pump rod 22 is reciprocably guidably received in housing in substantial alignment with the pump axis. One end of a pump arm 23 is bifurcated, forming a slotted opening adapted to receive the shank of said pump rod 22 and bear against one side of cushion assembly 24. Arm 23 further includes a rubbing end extending into the engine crankcase to engage a normally rotating eccentric cam or other engine element whereby the arm is rocked through pivot pin 20. At least one wall of housing 10 defines a spring chamber 17 and is provided with a threaded opening 26 to receive a sensor element 27 of the "pump alarm device.

Sensor element 27 includes basically an elongated body 28 having a partially threaded exterior, and a hexagonal head. A central bore 29 extends axially of the body and terminates at an inwardly projecting lip 31 which defines opening 32. A first elongated stationary contact 33 is fixedly positioned within the upper end of body 28, a part of which contact is normally disposed exterior to housing 10 to provide an electrical terminal. First contact 33 is insulated from the metallic body walls by grommet which forms a fluid tight closure. This insulating member is preferably formed of material such as a fuel resistant rubber which resists being affected by contact with fuel vapors.

Also retained within central bore.29 is a second, longitudinally slideable contact 34 comprising an elongated shank having a head 36 at one end and a protrusion 37 at the other end. A biasing member such as a coil spring 38 is retained between peripheral lip 31 and the lower or fusto-conical side of head 36, normally urging the movable contact through bore 29 to the extent that it will electrically engage tip 39 of stationary contact 33. Thus, a compartment is formed intermediate insulator 30 and head 36.

As shown in FIG. 2, with the sensor in open condition, the enlarged protrusion 37 of movable contact 34 extends outwardly and overhangs the end of body 38 beyond peripheral lip 31. This protruding portion 37 is sufficiently constricted in diameter to be registered in, and then traverse opening 32 such that the movable contact 34 might freely slide through axial passage 29 to engage the stationary contact 33 at such time as contact 34 is released. Contact 33 as previously mentioned, is maintained in its position by sealing grommet 25 which tightly fits within the end of passage 29 and thereby providing a closure to the latter.

Movable contact 34 is maintained in withdrawn position from the axial passage 29 as shown in FIG. 2, by a resilient, expandable retainer 41 carried under protrusion 37 and engaging a tapered shoulder 40. Movable contact 34 is in effect held in withdrawn position from bore 29 and spaced from contact 33 by a combined wedging and friction retention forces.

Retainer 41 constitutes a non-rigid washer-like member in the assembly, and is characterized by being preferably expandable, and secondarily adaptable to physical deterioration when subjected to vapors or direct contact with liquid in spring chamber 17. Retainer-41 is therefore formed of an elastomer or plastic material characterized 'by high swelling ability when affected by contact with a hydrocarbon fuel. For example, silicone rubber in the shape of a ring or washer which is sufficiently resilient to be forced over the broadest portion of the protruding tip 37 and yet, when properly positioned will be rigid enough to overcome the biasing force of spring 38 which normally urges contact 34 into bore 29.

It is understood that the specific. configuration of the expandable element 41 may vary from the washer-like element presently shown in so long as it performs the function of retaining the movable contact 34 in the position shown spaced from stationary contact 33.

The engaging surface 40 intermediate tip '37 and retainer 41 is preferably fusto-conicalin disposition to avoid the retainer being forcibly maintained in place by the bias of spring 38 regardless of expansion of the retainer. Thus, tapered surface 40 of tip 37 is formed with an included angle of approximately l0 to. 30 degrees. As the opening in retainer 41 enlarges underthe influence of fuel vapor, spring 38 will continuously urge contact 34 into bore 29 such that a vapor-tight annular seal will be maintained at the resilient member during the period of expansion.

When retainer 41 can no longer restrain movement of contact 34, the latter will slip through the retainer opening and immediately engage contact 33. This arrangement is endowed with the advantage that even though fuel vapors may accumulate in the pump spring compartment 17, such vapors will not enter bore 29 and create an explosive atmosphere in compartment 30 prior to the moment of engagement between the electrically contacting surfaces. Thus, should the latter create a spark, there will be no explosion.

A further precaution against vapor. explosion within the sensor element resides in the restricted annulus formed between opening 32 and protrusion 37 when the latter has been biased into the closed position. If for example the presence of fuel vapor within bore 29 should initiate an explosion, the narrow passage would restrain further propagation of the flame into the spring chamber.

ALARM CIRCUIT The electrical alarm circuit comprises basically a source of electric current such as a battery 42. as is normally found in an automotive system, together with ignition switch 43 operable to actuate at least part of the electric system. Also included in the electrical system is a suitable signal light 44 or other indicator, preferably carried on the automobile dash, where it will be visible to the vehicle operator at all times. Referring to FIG. 2, following preferred practice, the electrical circuit is grounded through battery 42, and includes a line connecting ignition switch 43 to stationary contact 33 of the sensor element 27. The sensor element circuit is grounded to the automobile chassis or to the pump body 10 through a condenser 35 when the contacts are closed.

With ignition switch 43 in closed position, the circuit through signal light 44 will not be closed-until such time as movable terminal 34 of the sensor element be grounded to the pump body. Grounding of the latter is achieved only at such time as movable contact 34 is released to engage stationary contact 33 whereby the circuit is completed through contact 34 and spring 38 to the pump housing and body 28.

Under normal operating conditions, fuel will be passed to pump inlet 46 into pumping chamber 18 and then discharged through pump outlet 47 as diaphragm 16 is reciprocated. However, should a malfunction in the diaphragm or other part of the pumpoccur as to permit leakage of the volatile fuel into spring compartment 17, retainer element 41 will come into immediate contact either with vapors or fuel or with the fuel itself. Over a relatively short period of time, retainer 41 will expand to the extent that said element is weakened and loses its ability to maintain the contact spring 38 in withdrawn position. Eventually retainer 41 will yield and deform under pressure of spring 38, permitting movable contact 34 to be urged into engagement with stationary contact 33. The alarm circuit will thus be closed through the pump housing as above noted. The affect of-this is that the signal light 44 will be actuated, giving the vehicle operator warning that fuel or fuel vapor-has passed from pumping chamber 18 into spring chamber 17 in anticipation of the pump becoming inoperable. This warning, of course, permits the operator to take the necessary precautions such as replacement of the pump to avoid a complete breakdown of the latter if the aggrevated condition continues.

It is understood that the principle of the herein disclosed apparatus may be accomplished by use of materials other than those specified. For example, in the instance of the deformable member, silicone rubber is found to possess the requisite strength and also the necessary rate of deformation to function as desired. There are however other materials which fullfil the basic requisite although exhibiting a rate of deformation that prohibits their use.

It should also be borne in mind that the present fuel pump as applied to normal automotive use operates within a temperature range of approximately 40 to 300 Fahrenheit. Consequently, the material appropriate to function in the disclosed arrangement is preferably stable within the noted temperature range. Further such temperature stability is deemed essential only if the alarm mechanism is to be triggered within a predetermined time limit after the exposure of the retainer member to fuel vapors.

I claim:

1. In combination with a diaphragm pump for volatile liquids including;

(a) a housing,

(b) a pumping chamber having inlet and outlet means,

(c) a second chamber in said housing including a diaphragm operating device,

((1) a diaphragm, separating said respective pumping and second chambers,

(e) an electrical circuit including;

(1) a source of electric current,

(2) an indicator for providing an alarm when activated to warn of the presence of vapors or liquid fuel in said second chamber,

(f) a deformable sensing element in communication with said second chamber and integral with said electrical circuit whereby when said sensing element is exposed to liquid or vaporous fuel, the latter will deform to actuate said circuit thereby activating said indicator to warn of the presence of fuel in said second chamber,

said sensing element including;

a body adapted to engage said housing,

a stationary contact sealably held in said body and forming a compartment,

a movable contact slideably positioned in said compartment and being biased toward said stationary contact,

retainer means engaging said movable contact for normally maintaining the latter in spaced relation to said stationary contact for holding said circuit in open position,

said retainer being disposed in communication with said second chamber to be exposed to vaporous fuel when the latter has leaked into said second chamber, and,

6 said retainer being formed of a material characterized by deformation thereof when exposed to fuel vapors whereby such deformation will release said slidable contact from its detained position to engage said stationary contact.

2. In the combination as defined in claim 1 wherein said retainer is compressibly held intermediate said body end and said movable contact thereby forming a vapor tight seal against passage of vapors into said compartment.

3. In the combination as defined in claim 1 wherein said body includes an opening at one end thereof, said movable contact includes a protruding head registered in said opening and extending from said compartment into said second chamber.

4. In the combination as defined in claim 3 wherein said moving contact includes;

(1) a constricted neck registered in said opening,

(2) and a protruding head depending from said neck,

(3) said retainer being carried on said neck and disposed in abutment with said head to be compressibly urged into sealing engagement with said body thereby forming a vapor tight seal to said compartment.

5. In the combination as defined in claim 4 wherein said head includes a tapered portion at one side thereof adjacent to said body, said retainer being compressibly disposed intermediate said tapered surface and said body to form said vapor seal.

6. In the combination as defined in claim 3 wherein said retainer includes;

(a) a resilient collar carried on said constricted member,

(b) said head including a tapered surface in abutment with said resilient collar and compressibly urging the latter into sealing engagement with said body whereby when said retainer is exposed to fuel and fuel vapors, said collar will expand thereby lessening the retentive force against said head and permitting said movable contact to be advanced toward said stationary contact while remaining in sealing relationship with said body during said movement of said movable contact.

References Cited UNITED STATES PATENTS 539,234 5/1895 Neu ZOO-61.04 2,386,412 10/1945 Wakefield 340-242 2,432,367 12/1947 Andresen 200-61.04 3,122,001 2/1964 Pritchett et al. ZOO-61.08 3,148,364 9/1964 Engles et al. 340-242 3,304,880 2/1967 Fold et al 103-150 3,381,591 5/1968 Toschkolf 103-150 ALVIN H. WARING, Primary Examiner D. MYER, Assistant Examiner US. Cl. X.R. 200-6104 

